What Metallurgical Grade Silicon Is
Metallurgical grade silicon is produced by carbothermic reduction of quartz in a submerged arc furnace and typically contains 98.5 to 99.5 percent silicon. It is the base material for aluminium casting alloys, for silicones and silanes, for the silicon used in solar and electronic feedstock, and for a range of metallurgical and chemical applications. Because it is an intermediate commodity rather than a finished product, it is bought against a grade designation and a size band, and the certificate of analysis for each lot is the primary quality document. Production is concentrated in regions with low cost electricity and reliable quartz supply, which shapes both the price level and the shipping patterns of the trade.
Grade Designation and the Resulting Price Band
The widely used designations 553, 441, 3303, 2202 and 1101 encode iron, aluminium and calcium in hundredths of a percent, so the first digit gives the iron level, the second the aluminium level and the third the calcium level. Moving from 553 toward 1101 means progressively less of each impurity, which requires cleaner raw materials, tighter furnace control and more careful selection of the finished product. Each step therefore commands a higher price per ton, and the spread between the cheapest and the cleanest metallurgical grade can be substantial. Buyers should match the grade to the actual process requirement rather than buying more purity than the application needs, because the extra cost is not recovered in the finished product.
Cost Build Up Behind the Per Ton Price
Quartz or quartzite is the source of silicon and its purity and lump size affect both yield and furnace stability. The reductant is a carefully balanced mix of low ash petroleum coke, charcoal and coal, and its reactivity and ash content strongly influence consumption. Electricity dominates the conversion cost, with typical consumption of 11,000 to 14,000 kilowatt hours per tonne, so smelter power contracts and regional tariffs are fundamental to the price offered. Electrode paste, refractories, labour, maintenance and environmental control add the remaining cost, and for export business the packaging, inland transport and ocean freight complete the delivered price.
Quotation Terms That Change the Number
A metallurgical silicon quotation is meaningless without its terms. The delivery basis may be free on board at the loading port, cost and freight, or delivered duty paid, and each adds a different amount. The size band, normally 10 to 100 millimetres but sometimes 10 to 50 millimetres or a crushed grade, changes the value of the material and the yield at the customer plant. Packing in one tonne big bags, twenty five kilogram bags or bulk changes handling cost. Payment terms, price validity and the treatment of moisture and fines also have a monetary value, and a quotation that appears cheap on a per ton basis may be more expensive once all of these terms are equalised. Buyers should always restate every offer on one common basis before ranking it.
Reviewing a Metallurgical Silicon Quotation
Start with the lot certificate of analysis and confirm that iron, aluminium and calcium are within the agreed grade band, then check the size distribution and the allowed proportion of fines. Confirm moisture content, net weight per bag and the total number of bags per container, and verify that the packing will survive the sea voyage and the customer handling equipment. Review the price validity, the shipment window and the documents to be provided, including the certificate of origin and any inspection certificate. Finally, check the tariff position and any trade remedy measure that applies to the origin, because duty can change the landed cost far more than a small difference in the quoted price per ton.
Frequently Asked Questions
Q: How much does a ton of metallurgical silicon cost?
The price depends on the grade designation, the size band, the delivery basis and the current level of furnace power and reductant cost, so it must always be quoted with these terms attached.
Q: What does the 441 grade designation mean?
It indicates roughly 0.4 percent iron, 0.4 percent aluminium and 0.1 percent calcium, which corresponds to a silicon content of about 99.0 percent or higher.
Q: Why does electricity dominate silicon cost?
Because the submerged arc furnace consumes roughly 11,000 to 14,000 kilowatt hours per tonne, so the local power tariff is the largest controllable element of production cost.
Q: Which reductants are used in silicon smelting?
A blend of low ash petroleum coke, charcoal and coal is used, selected for reactivity and ash content, because the reductant strongly affects furnace operation and product purity.
Q: What size band is normally traded?
Metallurgical silicon is most commonly supplied in a 10 to 100 millimetre band, with 10 to 50 millimetre and crushed or ground grades available for specific customer processes.
Q: What should be checked before placing an order?
The lot certificate of analysis, size distribution, moisture, packing and net weight, price validity, delivery basis, shipment window and the applicable duties at destination.